Conventional cooling units of telecommunications systems incorporate an electronic fan brake that stops the spinning fans when the power to the cooling unit is interrupted, such as when the cooling unit is removed from the associated shelf assembly. The intent is to prevent an operator that is removing the cooling unit from the shelf assembly and/or the fan from the cooling unit from being exposed to spinning fan blades, which spin at a relatively high velocity for newer telecommunications systems. As cooling requirements increase, the fans run at higher and higher speeds and take longer and longer to stop once the electronic fan brake is engaged. These fans can take 2 seconds or more to stop—longer than it takes to remove the cooling unit from the shelf assembly. This puts fingers and the like in danger.
Newer telecommunications systems utilize relatively large cooling units that are secured via a latch mechanism that is rotatably engaged and disengaged. The natural tendency of an operator when removing such a cooling unit is to place one hand on the latch handle and pull, thereby rotating the latch mechanism, using the other hand to take the weight of the cooling unit from underneath. This can result in a hazardous condition if the exposed fans are still spinning. As stated herein above, most conventional fans have a spin down time of several seconds, and are still spinning when the cooling unit is removed from the shelf assembly.
It should be noted that, in telecommunications systems that do not utilize an electronic fan brake, it is common to cover the fans with grates that have openings that are too small to admit a finger. Disadvantageously, these grates reduce the cooling performance of the fans and increase acoustic noise.
Thus, what is still needed in the art is an improved cooling unit that utilizes a latch assembly that triggers the electronic fan brake earlier, such that the fans are not still spinning when a cooling unit is removed from a shelf assembly. The present invention provides such an improved cooling unit, thereby minimizing the risk of operator injury.